Defining Hearing Loss Severity Based on Pure-Tone Audiometry and Self-Reported Perceived Hearing Difficulty: National Health and Nutrition Examination Survey.

Background:  There is a well-known metric to describe average/normal vision, 20/20, but the same agreed-upon standard does not exist for hearing. The pure-tone average has been advocated for such a metric.

Purpose:  We aimed to use a data-driven approach to inform a universal metric for hearing status based on pure-tone audiometry and perceived hearing difficulty (PHD).

Research design:  This is a cross-sectional national representative survey of the civilian noninstitutionalized population in the United States.

Study sample:  Data from the 2011-2012 and 2015-2016 cycles of the National Health and Nutrition Examination Survey (NHANES) were used in our analysis. Of 9,444 participants aged 20 to 69 years from the 2011-2012 and 2015-2016 cycles, we excluded those with missing self-reported hearing difficulty (n = 8) and pure-tone audiometry data (n = 1,361). The main analysis sample, therefore, included 8,075 participants. We completed a subanalysis limited to participants with "normal" hearing based on the World Health Organization (WHO) standard (pure-tone average, PTA of 500, 1000, 2000, 4000 Hz < 20 dBHL).

Analysis:  Descriptive analyses to calculate means and proportions were used to describe characteristics of the analysis sample across PHD levels relative to PTA. Four PTAs were compared, low frequency (LF-PTA, 500, 1,000, 2,000 Hz), four-frequency PTA (PTA4, 500, 1,000, 2,000, 4,000 Hz), high frequency (HF-PTA, 4,000, 6,000, 8,000 Hz), and all frequency (AF-PTA, 500, 1,000, 2,000, 4,000, 6,000, 8,000 Hz). Differences between groups were tested using Rao-Scott χ² tests for categorical variables and F tests for continuous variables. Logistic regression was used to plot receiver operating characteristic curves with PHD as a function of PTA. The sensitivity and specificity for each PTA and PHD were also calculated.

Results:  We found that 19.61% of adults aged 20 to 69 years reported PHD, with only 1.41% reporting greater than moderate PHD. The prevalence of reported PHD increased with higher decibel hearing levels (dBHL) categories reaching statistical significance (p < 0.05 with Bonferroni correction) at 6 to 10 dBHL for PTAs limited to lower frequencies (LF-PTA and PTA4) and 16 to 20 dBHL when limited to higher frequencies (HF-PTA). The prevalence of greater than moderate PHD reached statistical significance at 21 to 30 dBHL when limited to lower frequencies (LF-PTA) and 41 to 55 dBHL when limited to higher frequencies (HF-PTA). Forty percent of the sample had high-frequency loss with "normal" low-frequency hearing, representing nearly 70% of hearing loss configurations. The diagnostic accuracy of the PTAs for reported PHD was poor to sufficient (<0.70); however, the HF-PTA had the highest sensitivity (0.81).

Conclusion:  We provide four basic recommendations based on our analysis: (1) a PTA-based metric for hearing ability should include frequencies above 4,000 Hz; (2) the data-driven dBHL cutoff for any PHD/"normal" hearing is 15 dBHL; (3) when considering greater than moderate PHD, the data-driven cutoffs were more variable but estimated at 20 to 30 dBHL for LF-PTA, 30 to 35 dBHL for PTA4, 25 to 50 dBHL for AF-PTA, and 40 to 65 dBHL for HF-PTA; and (4) clinical recommendations and legislative agendas should include consideration beyond pure-tone audiometry such as functional assessment of hearing and PHD.